1. Field of Invention
The present invention is related to a fluid processing method of an object to be processed and an apparatus thereof required for the manufacturing process of thin film devices. In particular, the present invention is related to a fluid processing method of an object to be processed and an apparatus thereof suitable for a semiconductor manufacturing process that demands an extremely clean environment.
2. Description of Related Art
In recent years miniaturization of the structure of thin film devices such as semiconductors, liquid crystal displays and magnetic disks has been progressing and because of the performance of these devices and improved manufacturing yield rates, this is followed by expectations of extremely clean manufacturing processes. Looking at a semiconductor wafer as an example, the size of the foreign matter to be removed for a wafer of 0.2 um or more should be 10 parts or less per wafer, the amount of contaminants of metal ions should be 1010 atoms/cm2 or less, and the thickness of the oxide film formed by contact with air should be 1 nm or less.
Furthermore, the mixed production of multiple types of products become unavoidable making necessary equipment that can work with numerous manufacturing processes while putting sheet processing methods which process a plate-shaped object to be processed (hereinafter referred to as simply object to be processed) one wafer at a time.
As a first conventional example, FIG. 7 shows a substrate process of Japanese Patent Laid-open No.08-31690. In this conventional example, a plate-shaped object to be processed 53 is fixed to a substrate retention member 54 and also rotates (rotation means not shown in the figure). In order to prevent the front surface of the object to be processed from becoming contaminated due to the turbulent flow produced by the rotation of the plate-shaped object to be processed 53, the front surface of the plate-shaped object to be processed 53 is covered by a shielding plate 52 (hereinafter referred to front shielding plate) and a fluid process is carried out in which process fluid is injected onto the front surface of the plate-shaped object to be processed 53 only by means of a pure water injection nozzle 51. In this first conventional example, because a shielding plate (hereinafter referred to rear shielding plate ) is not provided on the rear surface of the plate-shaped object to be processed 53, the following problems occurred.
In addition to the fact that there was no fluid processing of the rear surface, the rear surface of the object to be processed became contaminated due to the turbulent flow generated by the rear surface of the plate-shaped object to be processed 53. When the rear surface of the object to be processed becomes contaminated, in processes after that the front surfaces of apparatuses such as a transfer arm for the object to be processed that makes contact with the rear surface of the object to be processed and a retention member for the object to be processed (not shown in the figure) undergo transfer contamination and the rear surface of the object to be processed after that becomes even more contaminated reducing the quality of the product. In particular, in processes which are subjected to heat, contaminants developed which were adhering to the rear surface of the object to be processed, reaching the front surface of the object to be processed which in turn caused fatal contamination on the front surface of the object to be processed.
As a second conventional example that can solve this problem, FIG. 8 shows a processing method of work and apparatus of Japanese Patent Laid-open No.08-78368. In this conventional example, the rear surface of the object to be processed is also covered by a rear shielding plate 62 to prevent the rear surface of the object to be processed from becoming contaminated due to the above-mentioned turbulent flow along with the front and rear surfaces of the object to be processed undergoing fluid processing simultaneously.
However, the object to be processed 64 in this example must be rotated in order to carry out uniform fluid processing on the front surface of the object to be processed. Considering this point, a retention means of the object to be processed 64 is mechanically provided integrally on the rear shielding plate 62 in this second conventional example and the object to be processed 64 and the rear shielding plate 62 are rotated simultaneously with a motor 65. The fluid is supplied from a supply tank 74 and is then switched by three-way valves 67, 68 and diverted to front shielding plate 61 and rear shielding plate 62. Although the connection structure of a supply pipe 76 to the rear shielding plate 62 is not mentioned in the second conventional example, the one rear shielding plate 62 rotates and the other supply pipe 76 is normally fixed. Further, the symbol 70 is a fresh fluid supply portion.
The following problems were present in the second conventional example however.
At first, because the fluid that processed the rear surface was contaminated, it cannot be re-utilized even if it is collected in a fixed hood 63. Because of this, fluid that was switched in a three-way valve 69 and collected in the fixed hood 63 had to be discarded. However, if discarded, large quantities of fluid are consumed. Further, looking at the system drawing of FIG. 8, although it can be seen that the fluid that processed the rear surface utilizes circulation, because the fluid that processed the rear surface has large contamination, circulation cannot be used even if the fluid is filtered by filters 72, 75.
Next, if the fixed supply pipe 76 that supplies fluid is connected to the supply opening provided on the rotating rear shielding plate 62 such that fluid does not leak, the connection portion will rub. Rubbing particles mix with the fluid contaminating the fluid and then pass through the fixed hood 63, a collection tank 71, a pump 73 and a supply tank 74 reaching to the front shielding plate 61 and then from the start the rear surface of the object to be processed contaminates the front surface of the object to be processed fatally reducing the quality.
If the fixed supply pipe 76 that supplies fluid and the rotating rear shielding plate 62 are connected such that they do not rub against one another, fluid will leak from the connection portion and in many cases corrosive material contained within the fluid will corrode parts such as the motor 65.
Thus, a method and an apparatus were not realized which carry out very clean fluid processing on the object to be processed in a sheet process that requires rotation of the object to be processed to allow uniform processing.
The topics of the present invention provide solutions to the above-mentioned problem points of the conventional examples. The first topic provides a fluid processing method of an object to be processed that uses circulation of fluid to allow very clean fluid processing at low-cost. The second topic provides a fluid processing apparatus of an object to be processed that allows very clean fluid processing of the front surface of the object to be processed and the rear surface of the object to be processed. The third topic provides a fluid processing apparatus of an object to be processed that can obtain a very clean object to be processed without generating rubbing particles and without fluid leaks.
The first method of the invention is a fluid processing method of an object to be processed characterized by the front and rear surfaces of the object to be processed being covered by a front shielding plate and a rear shielding plate in order to prevent the front and rear surface of the object to be processed from becoming contaminated and the object to be processed being allowed to rotate relative to the front shielding plate and rear shielding plate. This fluid processing method includes a process (1) wherein fluid is supplied between the front surface of the object to be processed and the front shielding plate and then a fluid process of the front surface of the object to be processed being carried out. Then, fluid is collected after the fluid processing of the front surface of the object to be processed completes and this liquid collected from the completed fluid processing of the front surface of the object to be processed is supplied between the rear surface of the object to be processed and the rear shielding plate and thereafter fluid processing of the rear surface of the object to be processed is carried out. This fluid processing method includes a process (2) wherein fluid being collected after the fluid processing of the rear surface of the object to be processed completes and this liquid collected from the liquid that completed fluid processing of the rear surface of the object to be processed is supplied between the rear surface of the object to be processed and the rear shielding plate and thereafter fluid processing of the rear surface of the object to be processed is carried out.
The object to be processed is a plate-shaped substrate such as a semiconductor wafer, glass for a liquid crystal display or a magnetic disk. The retention member for the object to be processed must be a material that can retain the object to be processed against centrifugal force generated by rotation.
In the first invention, fluid used in the processing of the front surface of the object to be processed is collected, this fluid is circulated and supplied to the rear surface of the object to be processed and processing of the rear surface of the object to be processed is carried out. It is not possible to collect fluid used in the processing of the front surface of the object to be processed and carry out processing of the front surface of the object to be processed again although, when the rear surface of the object to be processed has larger contamination compared to the front surface of the object to be processed, there are no hindrances even if fluid processing is carried out using fluid used in the processing of the front surface of the object to be processed. Because the processing of the front surface of the object to be processed is carried out by allowing fluid used in the processing of the front surface of the object to be processed to circulate, the amount of fluid used can be reduced making it possible to achieve low-cost fluid processing.
In particular, only the retention member for the object to be processed rotates excluding the hood and if the front shielding plate and the rear shielding plate are arranged so they do not rotate, the supply opening and the fluid supply system provided on the front shielding plate and the supply opening and the circulation system provided on the rear shielding plate do not generate rubbing particles making it possible to easily connect the supply opening and the circulation system provided on the rear shielding plate without a fluid leaks. Therefore, even cleaner low-cost fluid processing can be achieved.
Furthermore, in the first invention, a hood used to capture discharged fluid used in the fluid processing is arranged on the periphery of the object to be processed and designed to rotate on the same axis as the retention member for the object to be processed or the front shielding plate and the rear shielding plate. The rotation of this hood applies a centrifugal force to the discharged fluid from the completed fluid processing used in the fluid processing as well to the retention member for the object to be processed or the front shielding plate and the rear shielding plate and because of this only fluid that completed fluid processing discharged outward radially is captured and collected by the hood. Because the hood rotates along with the retention member for the object to be processed or the front shielding plate and the rear shielding plate, the centrifugal force acts on the discharged fluid that completed fluid processing which in turn controls the flow in the direction of the rotating axle of the retention member for the object to be processed or the front shielding plate and the rear shielding plate. Therefore, the discharged fluid that completed fluid processing is effectively collected in the collection portion without leaking from the direction of the rotating axle. Thus, because the hood is allowed to rotate and a centrifugal force is applied to discharged fluid as well as to the retention member for the object to be processed or the front shielding plate and the rear shielding plate controlling the flow in the direction of the rotating axle, the fluid can be effectively collected making it possible to achieve low-cost fluid processing.
Moreover, in the first invention, fluid that completed fluid processing of the front surface of the object to be processed can be mixed with fluid that completed fluid processing of the rear surface of the object to be processed and then collected. This collected fluid can be circulated and supplied to the rear surface of the object to be processed and then processing of the rear surface of the object to be processed carried out. According to this operation, because contamination of the fluid used in the processing of the rear surface of the object to be processed is diluted by means of mixing and collecting fluid that completed fluid processing of the rear surface of the object to be processed with fluid that completed fluid processing of the front surface of the object to be processed, processing of the rear surface of the object to be processed can be carried out by circulating the collected fluid to the rear surface of the object to be processed making it possible to achieve even more economical fluid processing.
Even further, fluid to be supplied in proportion to the processing that should be carried out for the object to be processed can be selected and processing of the front and rear surfaces of the object to be processed can be carried out. If a washing process is given as an example for the process that should be carried out for the object to be processed, three processes of washing, rinsing and drying can be done in one step. For this case, the washing fluid would consist of a fixed proportion of, for example, ammonia+hydrogen peroxide+water or hydrofluoric acid+water, the rinse would consist of super pure water and the drying would use an inert gas such as argon or N2 gas. According to this operation, because fluid to be supplied to the processing is selected and processing of the front and rear surfaces of the object to be processed is carried out, combining of processes can be designed improving the efficiency of the fluid processing even more.
The second invention is a fluid processing apparatus of an object to be processed that comprises a retention member for the object to be processed that retains the object to be processed, front and rear shielding plates which shield both the front surface and the rear surface of the object to be processed retained by the retention member for the object to be processed and rotate relative to the retention member for the object to be processed, a fluid supply system that supplies fluid between the front shielding plate and the front surface of the object to be processed through a supply opening provided on the front shielding plate, a hood that is arranged to rotate on the same axis as the object to be processed or the front shielding plate and the rear shielding plate and that receives centrifugal force generated by the rotation capturing the fluid that completed fluid processing of the front surface of the object to be processed and the fluid that completed fluid processing of the front surface of the object to be processed both discharged from the periphery of the object to be processed, a collection portion that collects said fluid that completed fluid processing captured by the hood from an outlet opening provided on the hood, and a circulation system that supplies the fluid that completed fluid processing collected by means of the collection portion between the rear shielding plate and the rear surface of the object to be processed through a supply opening provided on the rear shielding plate in order to carry out fluid processing on the rear surface of the object to be processed and then collects the fluid that completed fluid processing of said the surface of the object to be processed.
When fluid is supplied from the circulation system to the supply opening provided on the rear shielding plate, processing of the rear surface of the object to be processed is carried out. The liquid that completed processing of the front and rear surfaces of the object to be processed is captured by the hood and collected and mixed in the collection portion. At this time, because the fluid that becomes greatly contaminated due to the processing of the rear surface of the object to be processed is diluted by means of fluid wherein the contamination is halted at a comparatively small level due to the processing of the front surface of the object to be processed, the level of contamination is reduced. Therefore, by means of circulating this fluid mixture with a reduced level of contamination to the rear surface of the object to be processed, there are no hindrances to the fluid processing even if processing of the rear surface of the object to be processed is carried out.
In particular, when the front shielding plate and the rear shielding plate are fixed to the retention member for the object to be processed, the connections of a fixed type fluid supply pipe for the supply openings can utilize a fixed type method without generating rubbing particles and without leakage of fluid. Because fluid is supplied from the fixed type fluid supply pipe to the supply openings provided on both the fixed front shielding plate and rear shielding plate, the retention member of the object to be processed is mechanically provided integrally allowing a connection at the connection portion between the supply openings and the fluid supply pipes without generating rubbing particles and without leakage of fluid compared to a case when supplying fluid to supply openings provided on a rotating rear shielding plate. Therefore, very clean fluid processing with the addition of rubbing particles can be achieved. Corrosion of parts such as the rotation drive source due to corrosive materials contained within the fluid occurring because of fluid leaks can be prevented as well.
For a case when the retention member of the object to be processed is fixed and the front shielding plate and rear shielding plate are allowed to rotate, friction occurring in the connection portion is eliminated as much as possible using a bearing with a small amount of friction.
In the second invention, when the retention member of the object to be processed is allowed to rotate, this retention member can be comprised by a hollow rotating axle provided on the rear shielding plate wherein a supply opening is provided, a retention portion provided on the periphery of the object to be processed that retains the periphery of the object to be processed, and a linkage portion that protrudes from the rotating axle outward radially reaching close to the periphery of the rear shielding plate and that links the retention portion to the rotating axle. Further, the hood can be comprised by an external hood that covers the travel path of the fluid discharged from the periphery of the object to be processed and an internal hood that covers the lower portion of the travel path and in addition at least the internal hood rotates on the same axis as the retention member for the object to be processed.
Even further, the rotating retention member for the object to be processed and the hood can be comprised integrally or the retention member for the object to be processed and the hood can be formed separate and separate rotation control can be provided for either of them. A mechanism can also be provided that regulates the circulation flowrate of fluid in the circulation system and for this case, the mechanism that regulates the circulation flowrate can be a cyclone separator that utilizes the centrifugal force of fluid.
Moreover, it is preferable for the front shielding plate and rear shielding plate to be formed by carbon or fluoride resin. It is also preferable for the collection portion to be fixed and the outlet opening of the hood being inserted into this fixed collection portion without making contact.